Air officials will begin investigating several metal processing facilities near homes in Compton for a cancer-causing toxic recently found in the nearby city of Paramount.

The effort, announced Friday, comes after the South Coast Air Quality Management District discovered high levels of hexavalent chromium, a substance linked to lung cancer, coming from factories producing aerospace and manufacturing parts in Paramount. The findings last year raised red flags among environmentalists and prompted air officials to develop a regionwide plan to monitor facilities with similar profiles near homes, schools and hospitals.

The Compton investigation will mark the launch of the plan.

“We have learned from our intensive air-monitoring efforts in Paramount that some facilities previously unknown to emit high levels of hexavalent chromium are in fact significant sources,” said Wayne Nastri, head of AQMD in a prepared statement. “We will use the lessons from Paramount to determine whether there are any high emitters in Compton, and if so require them to rapidly reduce their emissions.”

Air officials chose Compton because several potential chrome-6 emitters are located near homes and businesses.

Sam Atwood, a district spokesperson, wouldn’t divulge what companies or areas of the city would be tested for fear of tipping off polluters, he said.

But, he noted, that six air monitors able to detect the toxic would be deployed.